Grate or stoker bar



April E2, 1938 e. A. KOHOUT ET AL I 2,114,147

GRATE OR STOKER BAR Filed Oct. 27, 1934 2 sheets-sheet 1 N N I N a & a

w 1 A N wfi T MINIMUM R LQ APFFEE 1938. G. A. KOHOUT ET AL 3459M? GRATE OR STOKER BAR Filed Oct. 27, 1934 2 Sheets-Sheet i5 Patented Apr. 12, 1938 UNITED STATES GRATE OR STOKER BAR George A. Kohout, Chicago, 111., and Al Wadewitz, Escanaba, Mich.; said Wadewitz assignor to said Kohout Application October 27, 1934, Serial No. 750,260

4 Claims.

This invention relates to grates for furnaces and more particularly to improvements in grates of the stoking type such for example as is shown in the patent to Kohout Number 1,355,095.

It is a purpose of this invention to provide a grate bar which will provide a large amount of surface for cooling below the top of the bar.

It is a further purpose of this invention to provide a grate bar which shall consist of a multiplicity of independent elements assembled together in such a fashion as to permit a certain amount of expansion and thus avoid settin up excessive stresses in the bar which would cause it to break.

It is a further purpose of the invention to provide a bar of this character with a shield that is ventilated and yet reduces sifting of material therethrough to a minimum.

It is further a purpose of the invention to provide a bar of this character wherein the several elements are so connected with each other and the support as to be movable with respect to each other and give enough to dislodge any accumulation or adherence of ash or clinker.

Other and more specific objects and advantages of the invention will appear as the description proceeds in connection with the accompanying drawings wherein the preferred form of the invention is shown. It is to be understood, however, that the drawings anddescription are illustrative only and are not to be taken as limiting the invention except in so far as it is limited by the claims.

In the drawings- Fig. 1 is a front view of a grate bar embodying the invention;

Fig. 2 is a section on the line 2-2 of Fig, 1 showing the face of the end element;

Fig. 3 is a section on the line 3-3 of Fig. 1 showing the side face of an intermediate element; Fig. 4 is a section on the line 4-4 of Fig. 1 showing the side face of the element to which the grateoperating rod is secured;

Fig. 5 is a plan view of a portion of the bar; and

Figs. 6 and 7 are fragmentary sectional views showing the manner in which the end elements are secured in the grate bar.

Referring now in detail to the drawings, the grate bar [0 is mounted in the usual fashion by means of the trunnions II and I2 in the side frame members l3 and I4 so that the same may be rocked back and forth. These trunnions are mounted on the two end elements l5 and I6 of the grate bar. The end elements 15 and 16, one

of which is shown in Fig. 2, are duplicates with the exception that one is a right hand and the other is a left hand element. Preferably, the members H and 12 are an integral part of the elements l5 and I 6. 5

The grate bar It! is made up of a number of elements including the elements 15 and I6, filler elements such as IT shown in side view in Fig. 3, and drive elements l8 and I9, the drive elements being the ones which have the extended portions 10 for connection to the operating rods or bars for the grates. Adjacent to the end member [5 and throughout the body of the grate, the elements I! are all the same in structure, but between the drive element l9 and the end element I 6 the 15 filler elements H are reversed, that is to say they are right hand elements where the elements I! are left hand elements.

Each of the elements l1, l1, l8, and I0 have three transverse apertures therein at 20, 2|, and 20 22 to receive the square bar 23 and the round rods 24 and 25 on which the various elements are threaded. The end elements 15 and I5 have sockets as indicated at 26 and 21 for the rod 25, and sockets 28 and 29 for the rod 24. The rec- 25 tangular bar or rod 23, however, extends through the elements I5 and I6 and is provided with the washers 30 and 3| welded or otherwise suitably secured to the rod 23 for holding the elements assembled on the rods. All of the elements have 30 a back side which is substantially fiat, and, on the front side thereof, the elements are provided with three projections for engagement with the back side of the next adjacent element. These three projections are indicated in Figs. 3 and 4 35 at 32, 33, and 34. On the end elements, however, the elements are strengthened and a projection is also provided by extending a flange around the rod 23 as shown at 35 to provide the third bearing projection. 40

Inspection of Figs. 1-3 will show that projection 32 is above the top rod 25 and close to the hot surface of the grate bar. Excessive expansion must be guarded against and therefore the projections 32 are made slightly shorter than the 45 projections 33 and the projections 33 are slightly shorter than the projections 34. This allows more expansion for the tops of the elements of the bar and prevents warping or breaking of the grate bar. Further safety is obtaineddue to the 50 fact that rod 25 does not hold the elements from spreading at the top if the clearance provided by projections 32 is insufficient to take care of some unusual expansion.

The various elements of the grate bar are thus somewhat loosely held together in the sense that, although apparently rigid, there is sufficient yield in the assembly to avoid undue stresses when the grate bar is heated up since each element is free to adjust itself or give slightly on the various rods, and, naturally, there is some little play in assembling this large a number of elements upon the three rods. For example the openings for bar 23 are made a little too large so the elements have a little play thereon. Thus if bar I9 has the rocking force applied to it, that end of the bar will turn slightly more than the other end.

The top surfaces of the various elements have the side edges thereof provided with the spaced teeth as indicated for example at 36 in Figs. 2 to 5. These teeth form barriers so as to provide support for the larger particles and yet permit the fine ash and burned material to drop through the grate and to permit air to pass up through the grate for burning the fuel.

The shield portion 31 is provided on each of the elements, but, in contrast to its structure on the Kohout patent hereinbefore mentioned, this shield, when the elements are assembled, presents a series of spaced shields which permit the air to circulate between them so as to aid in cooling. The actual clearance, however, is so small as to avoid any substantial amount of material passing through the spaces between the shields on the several elements. For example, the spacing is in the neighborhood of $5 of an inch between the elements.

It will be noted from an examination of Fig. 1 that the element 19 is illustrated as changing from a left hand element to a right hand element. That is to say, the elements on the left of Fig. 1 have the teeth 36 on the right hand side thereof, while the elements to the right of the element l9 have the teeth on the left hand side thereof. The element l9, therefore, is provided with relatively shallow teeth as indicated by the dotted line in Fig. 1 while the teeth on the adjacent elements are much deeper as indicated by the dotted lines thereon. Preferably, the element I9 is originally constructed substantially like the element l8 and is then ground down for any particular installation to obtain the exact length of grate bar desired. This accounts in the present showing for the shallow groove in the element l9 although it is obvious that the depth of the grooves may be varied without in any way departing from the spirit of the invention. This characteristic of the grooves in the element I9 is merely brought out to show how the overall length of the grate bar may be varied to fit a specific installation even where the addition or leaving out of one of the elements I! would not make a close fit.

Referring now to Figs. 6 and 7, the manner of fastening the elements upon the rods 23, 24, and 25 is more clearly illustrated. As shown in Fig. 7, the rod 23 passes through a rectangular opening in the end element l5. Then the end of this rod is reduced to provide a round extension 38 to receive the washer 30, and the washer is secured in place, for example, by welding at 39. This, obviously, is not the only feasible way of securing the elements together as this may readily be accomplished by merely passing a rivet or bolt, set screw or the like, as shown at 40, through the end pieces [5 and I6 and into the rod 23.

Because of its flexibility, this bar can be operated to break up clinker that forms in a sheet on the top surface thereof. Force applied to either element [8 or element l9 separately causes a slight twisting of the bar which will break the clinker up into small sections without damage to the bar.

From the above description, it is believed that the construction and advantages of this device will be clear to those skilled in this art.

Having thus described one specific form of the invention, what we claim as new and desire to secure by Letters Patent is:

1. A grate bar of the character described comprising a plurality of grate bar elements each having a fuel receiving face and having on one side thereof projections adapted to engage the next adjacent element for spacing the elements, said elements being spaced apart below the fuel receiving surface except for said projections whereby to present a large amount of cooling surface below the top of the grate bar, said projections decreasing in length toward the top of the bar to provide for more expansion of the elements at the top than at the bottom of the bar, and means below the top of the bar loosely securing said elements together.

2. A grate bar comprising a pair of end elements provided with trunnions for pivotally supporting the bar, intermediate driving elements having depending arms for connection to an operating mechanism, and filler elements interposed between said end elements and said intermediate elements together with tie rods running lengthwise of the bar through the filler and driving elements, said rods being spaced apart vertically, and at least one of said rods having means thereon cooperating with the end elements to hold said elements assembled together, said rods comprising upper and lower rods terminating in the end elements and an intermediate rod passing through the end elements and having means to hold the elements together on said rods.

3. A grate bar for furnaces comprising a plurality of grate bar elements each having a fuel receiving face, and each having depending therefrom a web portion provided at one edge with a curved shield flange, means securing said elements together side by side, and spacing means on the web portions of said elements cooperating with said securing means to hold said elements in alignment, said spacing means being shortened toward the top of the bar to provide for vexpansion, and said securing means being close to the bottom of the bar.

4. A grate bar comprising a plurality of relatively thin elements each having a fuel receiving face at the top edge thereof, a rod on which said elements are threaded, said rod having means at its ends to prevent removal of the elements therefrom, said rod lying close to the bottom edge 

